1. Field of the Invention
This invention relates to the production of carbon black.
2. Description of the Prior Art
The rubber industry currently accounts for essentially all of the usage of carbon black. In turn, predominantly all of this usage is for the purpose of reinforcing rubber compounds in the fabrication of automobile, truck and off-the-road vehicle tires. Since the carbon black component amounts to 30-35% of the weight of such rubber compounds, the consumption of this commodity is understandably vast.
Carbon black for the manufacture of tires is produced by the so-called oil furnace process. This process as generally practiced today basically involves contacting atomized droplets of an aromatic-rich hydrocarbon feedstock with a turbulent mass of combustion gases resulting from burning a mixture of methane and excess pre-heated air. In accordance with the foregoing process, a major portion of the feedstock is pyrolytically dissociated in a partial oxidation reaction to provide a substantial yield of carbon black in the form of an aerosol whence pulverulent black is recovered, usually by filtration, and thereupon pelletized for the market.
The oil furnace process by its very nature is energy intensive. For example, at the current price of natural gas to the industry about 15% of the cost to produce one pound of a high grade black is attributed to this feed to the process. Since the future portends a substantial increase in the cost of natural gas over and above the other cost factors involved in producing carbon black, an alternate fuel source of more stable pricing prospects is particularly indicated. While normally liquid paraffinic hydrocarbons such as the various grades of fuel oil possibly meet this criterion, their attractiveness as an alternate fuel is more apparent than real. This is so primarily because fuel oils are comparatively difficult to combust in the present context requiring a plurality of atomizing nozzles which are prone to cause coking problems in the high temperature environment involved. Beyond maintenance and downtime problems, the use of fuel oils can also adversely affect quality of the carbon black product.